Graded Channel FETs for Navy Electromagnetic Systems.
Abstract
This report summarizes the results of a program for development and evaluation of gallium arsenide field effect transistors (FETs) having graded doping profiles in the direction perpendicular to the surface. During the course of this program, such graded channel FETs were shown to be more linear than conventional FETs with flat channel doping profiles. Graded channel FETs are expected to be very beneficial for advanced microwave systems requiring highly linear solid state amplifiers. Included in the scope of the program was an analysis of the effects of graded profiles on linearity, the development and implementation of a method to grow epitaxial layers having graded profiles, fabrication and dc and rf characterization of graded channel FETs, development of a localized anodic oxidation procedure to utilize n(+) contact layers, and an objective comparison of the properties of graded channel FETs with those of conventional, uniformly doped structures. Theoretical analysis of the effect of nonuniform doping profiles showed that improved linearity is expected for profiles in which the doping concentration is greater near the active channel/buffer interface. For a given channel thickness and total doping concentration, the device having the largest 'charge moment' (the integral across the active layer of the product of doping concentration and distance from the surface) was predicted to be more linear.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1978
- Accession Number
- ADA060350
Entities
People
- D. W. Shaw
- E. C. Secrest
- R. E. Williams
Organizations
- Texas Instruments